Topic: 788ci HD DI - GPS speed issue

[zach]

So I finished installing my 788ci HD DI yesterday. Turned it on, and while navigating though the screens noticed that my GPS speed was not zero and was jumping up to 1.0 mph while sitting in my driveway. I figured it was the software version and updated to version 6.25. However it was not fixed by upgrading, and I still get a GPS speed reading from between 0.0 and 1.0. Is this normal, and is there any way to fix it?

[sonar2000]

It is normal for the speed to vary when sitting still as the unit cannot get an exact location on your and the difference in the error position causes the speed to fluctuate since it thinks you are wandering.

I would not pay any attention to it since it is normal..

Chuck

[George]

zach

Chuck is correct, I have had my unit on in my driveway for up to 4 hours, and the GPS tracks go all over the place and speed increase and decreases.  Have not done since last year, but I also did the same thing when I lived in California and the same thing happened.  I am using an 1197 and an 1198, it is not the unit but how the GPS sees the satellites, which are continually changing.

George

[zach]

Thanks for the info guys. I'm hoping to try it out this weekend.

Zach

[W9GFO]

Most GPSs will "lock" onto a location when the calculated position does not change beyond a certain threshold. This can give a false sense of accuracy, but it takes care of false speed readings pretty well.

Larger threshold gives a steadier reading at the sacrifice of response time. Automotive units may have a large threshold - you may need to move a few dozen yards before it reports that you are moving.  Smaller thresholds respond better but it can make it look like you are moving when you are not. A handheld may have a "walk" mode where it lowers the threshold so that it shows small movements.

There is not one perfect threshold. It would be a nice feature to be able to adjust it to suit.

[gwraith]

Correct me if I am wrong but I was under the understanding that it was not good to run your Humminbird when the transducer was out of water.  According to the Humminbird site it can cause damage to the unit itself and/or the transducer.

[ITGEEK]

I don't think this will hurt anything.
I've done it lots of times.
The transducer is just sending out pings and listening for the returns.
On dry land, they just won't return through the air.

[sonar2000]

The only thing that I can remember on cables is that you dont put a long cable extender on with out a transducer as that will or can cause burn out problems.  You can run a unit with out a transducer or gps connected. Just dont have a cable on the unit not connect to anything..Unless it is like the T3 or U3 switch.

Chuck

[Humminbird_Greg]

Most GPSs will "lock" onto a location when the calculated position does not change beyond a certain threshold. This can give a false sense of accuracy, but it takes care of false speed readings pretty well.

Larger threshold gives a steadier reading at the sacrifice of response time. Automotive units may have a large threshold - you may need to move a few dozen yards before it reports that you are moving.  Smaller thresholds respond better but it can make it look like you are moving when you are not. A handheld may have a "walk" mode where it lowers the threshold so that it shows small movements.

There is not one perfect threshold. It would be a nice feature to be able to adjust it to suit.

We report exactly what the GPS Receiver calculates as the speed and direction – other companies filter or use a threshold as W9GFO explained.  I like the idea and being able to set this, could you add that to the Wish List on this web site W9GFO?

[Humminbird_Greg]

Correct me if I am wrong but I was under the understanding that it was not good to run your Humminbird when the transducer was out of water.  According to the Humminbird site it can cause damage to the unit itself and/or the transducer.

Where did you read this gwraith? 
This is not correct and I will ask it to be removed/changed.

[Weekend Warrior]

I think maybe gwraith is possibly misremembering(lol)where he read that, but I DID read it here:  http://forums.sideimagingsoft.com/index.php?topic=2986.msg16960#msg16960
by Mr. Gecy.  The first paragraph in red.  I took it as gospel too given his creds....  It is an older post, so perhaps it was long held myth that was recently debunked...  Don't know.

Mark

[Humminbird_Greg]

Hopefully Robert will see this message and edit his post.

[sonar2000]

Greg, I was told this also a while back by customer service. It was said that the extention cable for the transducers should not be installed on the unit and then powered on with out the transducer being connected.
something about the impedence of the cable would cause the transmitter to fry with out the termination resistance of the transducer.

I think you and I had this conversation about a year ago also....
Please check on this with enginering and verify as we dont want to harm the units..We run the T3 switch and then have an extension cable for the portable mounting convience.
Chuck

[Humminbird_Greg]

Chuck,
No one mentioned an extension cable. Let’s keep this on subject: Robert and gwraith’s statements were about the transducer.  Running the transducer without the transducer being in the water will not hurt the transducer or the unit.

[gwraith]

Greg and Others.  Here is the diredt quote from the Humminbird FAQ section:

"I am having problems with my depth reading. What should I check?



Checking for depth while your boat is parked in your driveway or yard, or testing the transducer in a swimming pool, bucket of water or barrell is not an accurate test for sonar.  All tests should be conducted in a lake, pond, river or sea.  Testing your transducer while out of the water can damage the transducer, the unit or both.  "

Greg are you saying that it is ok to run the unit with the transducer out of the water?

[Humminbird_Greg]

Thanks gwraith, I found the FAQ you referenced and have asked that it be corrected.

Yes I am saying that it is safe for your unit and transducer if you run them out of the water.  Think of the number of fishermen who run bow mounted units that have their transducers mounted on the trolling motor.  All of them do not turn these off when moving from one location to the next.  Also there are those of us who do not turn everything of when we trailer the boat… If it damaged our units or transducers, than the internet would be abuzz with Customers complaining about this.

[gwraith]

Greg:  Thanks for the quick reply and for clearing up the confusion.

Gary

[gwraith]

Greg:  There is another instance on the Humminbird FAQ site that references testing the transducer out of water.  Here is the quote:

I am having problems with my depth reading. What should I check

Testing your transducer while out of the water can damage the transducer, the unit or both. No Depth Consult the Common Checks guide and make sure that all ...


www.humminbird.com

Gary

[ITGEEK]

Greg,
Something just popped into my head.

If the transducer is out of the water and is pinging, and
there is no return, will the unit try it's best to get a
signal, and ping faster, and maybe even increase the ping
power level?

I'm just wondering if prolonged use out of the water will
cause the transducer to ping a lot more than normal, which
would cause it to wear out a little faster.

[Humminbird_Greg]

When the transducer is out of the water the unit will try and get a depth reading.  That means that it will switch to its highest power level and slow down the ping rate (it has to slow down to allow sonar readings from a deeper water depth which will take longer).

I don’t know that transducers wear out or have a limited number of pings in them.